Image detecting systems typically scan scene based images onto a focal plane array made up of individual detector elements in order to detect viewed images. Each detector element within the focal plane array has a unique and different output voltage offset and gain reported upon detection of an image. These unique and different output voltage offsets and gains of the individual detector elements are a result of an inherent inability to produce identical detector elements during the manufacturing process. The inability to produce identical detector elements requires that an imaging system perform calibration on the focal plane array to compensate for the varying initial output voltage offsets and gains from one individual detector element to another despite detecting identical portions of an image.
Calibration of image detecting systems typically requires that calibration reference levels be viewed by the focal plane array during system operation. This calibration requirement can take time away from viewing the actual scene images. The calibration references of typical scan systems are thermo-electric devices that are optically viewed during the calibration period. However, these calibration references only provide an approximation of scene based energy and thus calibration is not performed on actual images. Therefore, it is desirable to perform calibration with actual scene based energy collected within a typical scan cycle.